Efficient Spin-Light Emitting Diodes Based on InGaN/GaN Quantum Disks at Room Temperature: A New Self-Polarized Paradigm
Efficient Spin-Light Emitting Diodes Based on InGaN/GaN Quantum Disks at Room Temperature: A New Self-Polarized Paradigm
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DOI：
10.1021/nl5003312
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发表时间：
2014-06-01
期刊：
影响因子：
10.8
通讯作者：
Chen, Y. F.
中科院分区：
文献类型：
--
作者：
Chen, J. Y.;Ho, C. Y.;Chen, Y. F.
设计、制备了一种由InGaN/GaN多量子盘(MQD)、铁磁接触和Fe3O4纳米粒子组成的性能良好的自旋发光二极管(LED)。在0.35T的低磁场下，室温下电致发光的圆极化度可以达到10.9%，克服了氮化物半导体中由于弱自旋轨道相互作用而产生的很低的自旋极化度。在这个新设计的设备中，几个潜在的机制同时扮演着重要的角色，以实现如此高的性能。最重要的是，纳米盘之间的空位可以由具有合适能带排列的半金属纳米颗粒来填充，这使得自旋极化的电子和空穴能够选择性地转移，从而增强了LED的输出自旋极化。与以前报道的机制不同，这一新过程导致了自旋弛豫对温度的弱依赖性。此外，在纳米盘的形成过程中，平面InGaN/GaN多量子阱中的内部应变可以松弛，从而导致Rashba哈密顿量的消失，提高了自旋弛豫时间。因此，我们的方法为半导体自旋电子学的进一步研究和发展开辟了一条新的途径。
A well-behaved spin-light emitting diode (LED) composed of InGaN/GaN multiple quantum disks (MQDs), ferromagnetic contact, and Fe3O4 nanoparticles has been designed, fabricated, and characterized. The degree of circular polarization of electroluminescence (EL) can reach up to a high value of 10.9% at room temperature in a low magnetic field of 0.35 T, which overcomes a very low degree of spin polarization in nitride semiconductors due to the weak spin orbit interaction. Several underlying mechanisms play significant roles simultaneously in this newly designed device for the achievement of such a high performance. Most of all, the vacancy between nanodisks can be filled by half-metal nanoparticles with suitable energy band alignment, which enables selective transfer of spin polarized electrons and holes and leads to the enhanced output spin polarization of LED. Unlike previously reported mechanisms, this new process leads to a weak dependence of spin relaxation on temperature. Additionally, the internal strain in planar InGaN/GaN multiple quantum wells can be relaxed in the nanodisk formation process, which leads to the disappearance of Rashba Hamiltonian and enhances the spin relaxation time. Our approach therefore opens up a new route for the further research and development of semiconductor spintronics.